1. Field of the Invention
The present invention relates to a method of managing data stored on a recording medium such as an optical disk.
2. Related Background Art
Currently the storage capacity of a data recording medium, such as a semiconductor memory card used in a digital still camera and a magneto-optical disk used in a digital disk recorder, has dramatically increased. Therefore, users can record a wide variety of data contents, such as a moving image, a sound, and a still image on the above data recording media.
FIG. 9 shows a configuration of a camera integrated-type disk recording and reproducing apparatus 900 as an example of product forms employing such a data recording medium.
For the disk recording and reproducing apparatus 900, the recording operation will be described first. The reference numeral 901 denotes a video input device which outputs a video signal obtained by photographing an object. The reference numeral 902 denotes an audio input device which outputs an audio signal collected usually by using a microphone. The reference numeral 903 denotes a video encoder which encodes the input video signal. The reference numeral 905 denotes an audio encoder which encodes the input audio signal. The reference numeral 907 denotes a multiplexer which multiplexes the encoded video data and the encoded audio data and performs synchronous control of the encoded video and audio data.
The reference numeral 909 denotes a disk controller which performs reading of and writing on a disk medium 912. The reference numeral 910 denotes a control unit which performs the control of the overall disk recording and reproducing apparatus 900. The reference numeral 912 denotes the disk medium (DISK) which stores the multiplexed and encoded video and audio data. The reference numeral 913 denotes a display device which displays a status of the apparatus, various kinds of setting screens, and a display image concerning the input video signal and the reproduced video signal. The reference numeral 914 denotes a speaker device which outputs the input audio signal and the reproduces audio signal. The recording operation is performed by the above-described configuration.
The reproducing operation will now be described. The reference numeral 911 denotes a shock-proof memory, and the shock-proof memory 911 is one which is used to temporarily store the data read out from the disk medium 912 and read out the data to supply the read out data continuously during a period when the disk medium 912 is not accessible due to vibration or shock. Further, in the recording, sometimes the shock-proof memory 911 is also used as a buffer when writing can not be performed onto the disk medium 912 due to the vibration.
The reference numeral 908 denotes a demultiplexer which performs demultiplexing and reproduction synchronous control of the reproduced and encoded video and audio data. The reference numeral 904 denotes a video decoder which decodes the encoded video data. The reference numeral 906 denotes an audio decoder which decodes the encoded audio data. The decoded video signal is subjected to reproduction display on the display device 913, and the decoded audio signal is subjected to reproduction output by the speaker device 914. In the reproduction, similarly to the case in the recording, the control unit 910 also performs the control of the overall disk recording and reproducing apparatus 900 and response to various kinds of functional requests from the user. The reproducing operation is performed by the above-described configuration. For example, the above-described disk recording and reproducing apparatus is disclosed in Japanese Patent Application Laid-Open No. 2002-314916.
The encoding/decoding processing of the video data and the encoding/decoding processing of the audio data are often attained with a common unit in the disk recording and reproducing apparatus. In FIG. 9, the video encoder 903 and the video decoder 904 are expressed in the form of a video codec 915 which is of the common unit, and the audio encoder 905 and the audio decoder 906 are expressed in the form of an audio codec 916 which is of the common unit. Further, the multiplexer 907 and the demultiplexer 908 are also expressed as a common unit (MUX/DMUX) 917.
In the usual apparatus which can record and reproduce the moving image, an encoding format of an international standard specification which is prescribed by MPEG (Moving Picture Experts Group) is often used as the method of encoding the video and audio data. The encoding format specifically includes MPEG-1, MPEG-2, MPEG-4, and the like.
The encoding formats such as MPEG-1, MPEG-2, and MPEG-4 only define a compression method and syntax of each medium. Without modification, in some cases, it is difficult that such the encoding format is handled as an individual application. Therefore, a container format which is easier to handle is usually used for the application of the personal computer and the like.
Specifically, the container format includes QuickTime (trademark), MP4, AVI format, and the like. The container format usually supports the plurality of audio and video encoding methods which is not limited to the MPEG. The reproducing application is characterized in that decoding processing is performed in such a manner that a built-in decoder is changed for each file by detecting an identifier expressing the encoding method set in the file.
As shown in FIG. 7, there are a built-in type and an external reference type as types of container formats. The built-in type has the configuration in which all media data (audiovisual stream) and attribution data are built in as one container file 701. The external reference type is one which externally refers to the media data (audiovisual stream file). The external reference type has a configuration in which the media data independently exists as a different file 702 and only attribution data of the media data and information designating a target reference of an external file are included as a container file 703.
The built-in type has in the container file 701a storage area 701a for the audiovisual stream and a storage area 701b for information designating an attribution of the audiovisual stream. In the external reference type, the audiovisual stream is filed and arranged in the external file 702, and the container file 703 has a reference designation area 703a for the external file 702 and an attribution designation area 703b. 
Specifically, a file pass of the external file 702 in which the audiovisual stream exists is described in the reference designation area 703a of the external file 702. Sometimes a serial number (volume ID) of the recording medium is added to the file pass.
While the information designating the attribution of the external file 702 is stored in the attribution designation area 703b, in addition to environmental data such as recording data, file offset data is also often stored in the attribution designation area 703b to more efficiently perform random access reproduction of the data stream in the audiovisual reproduction. The file offset data is one which shows a relationship between the number of frames or time and a position of a file pointer.
UDF (Universal Disk Format) defined by OSTA (Optical Storage Trading Association) is already widely adopted as a file system in the disk medium such as a CD (Compact Disc) and a DVD (Digital Versatile Disc). Conformity to the file system such as UDF allows disk access independently of the apparatus and the operating system. In UDF, a function called a descriptor is used for defining a volume attribution or a file attribution of the disk medium.
The descriptor comes in many varieties, and FIG. 8 shows an example of descriptors. In the example shown in FIG. 8, a descriptor 800 is a definition of a file entry, and creation/change data, a recording format, and a file protection attribution can be written as the attribution.
However, the above-described method has the following problems.
The disk medium complying with UDF is not dependent on the apparatus and the operating system, and the disk medium can be directly mounted on various systems. However, in the case where the data stored in the disk medium is of an audiovisual standard which is not supported by the specific operating system or application, sometimes the data can not be reproduced, while the disk medium can be mounted.
In the case where the container format is used, there is a restriction in the video codec and the audio codec supported by the container format. Therefore, even if the audio visual data can be reproduced on the disk recording and reproducing apparatus, sometimes the audio visual data can not be reproduced when copied in a hard disk drive or the like in the external personal computer (PC).
Further, when the external reference type container format is used, the file pass of the target reference becomes different after the file is copied or moved, and sometimes the audiovisual data can not be normally reproduced.